Sickle fired upon shipping in Mitylene Harbour and was engaged in gunfire with German patrol vessels GA76 and GA91 during which Able Seaman Richard Blake, a member of the submarines 3 inch gun crew who was blown over board. The submarine had to make an urgent dive to avoid further hits, and Blake was left in the water and picked up by the Germans to become a POW. Sickle escaped the engagement and continued on her patrol